I just install thunderbird-17.0.3 and it work out of the box by following below instruction...it just need gnupg (should be come as default in VL 7.0), enigmail and thunderbird...there is no need to install pinentry...

ok...i figure out what is the problem now...the problem is enigmail will use gpg-agent for the passphase input if it detect a gpg-agent running as a daemon...while in VL7.0 gpg-agent is not running at startup that why it will use enigmail for passphase input...in VL7.1 the gpg-agent is auto started as default and you will need pinentry for the passphase input

below link show there is a workaround if you dun want to use pinentry...you can find the enigmail.js under$HOME/.thunderbird/xxxxx.default/extensions/{xxxxxx}/components and modify it according the links